SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00b8751cc270ee01c3f286b444dde45a1d019ec5aac53630faff9a4962859ea4' 
  AND token = '56cOJZU7ns1GirlvcYE49x1lRTxQ2fJKVUhGlHmnZxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}